environmental engineers have adopted a pragmatic and scientific-based approach in
assessing and predicting the ecotoxicological effects.
Trophic Levels & Batteries of Assays The approach considers the key structural
pillars of biological communities, i.e., trophic levels. In principle, representatives of
biological species from the groups of producers (autotrophic organisms like algae
and plants), consumers (invertebrate and vertebrate animals), and decomposers
(microorganisms)
1 are selected as model organisms and used in batteries of bioassays for testing of ecotoxicity.
The bioassays recommended for ecotoxicity testing within regulatory frameworks (including chemical safety as well as risk management and remediation)
need to be validated to assure repeatability and quality of the results using standardized guidelines that are currently available through international organizations
such as OECD or ISO.
The broadly used bioassays recommended by regulations include usually
short-term exposure (acute) tests. These have both advantages (e.g., possibility
to maintain the model organisms in laboratory, good standardization, time and
cost-effectiveness) and disadvantages (lower sensitivity in comparison to wild
species, lower representativeness for environmentally relevant long-term chronic
exposures, etc.).
• Aquatic Environment The most commonly used assays are 72–96 h algal
growth inhibition test with, e.g., Scenedesmus subspicatus (OECD 2011),
24–48 h immobilization test with crustacean Daphnia magna (OECD 2004),
96 h acute test for lethality with adult fish (OECD 1992), currently promoted
alternative 96 h toxicity test with zebrafish Danio rerio embryos (OECD 2013),
and 16 h bacterial growth inhibition test with Pseudomonas putida (ISO 1995)
• Terrestrial and Soil Environment Commonly used bioassays include 7–14-day
acute test for lethality with earthworms Eisenia fetida (OECD 1984; ISO 2012a),
96 h root elongation test with plants, e.g., Lactuca sativa (OECD 2006a; ISO
2012c), 24 h acute test for lethality of nematode Caenorhabditis elegans (ASTM
2014), or 6 h test for effects on microbial nitrification in soil (ISO 2012e).
Standardized longer exposure assays testing for population-relevant endpoints
such as reproduction are also available. For example, 21-day reproduction test with
D. magna (OECD 2012) or reproduction test with enchytraeids (ISO 2014b; OECD
2016a), springtails (ISO 2014a; OECD 2009), and earthworms (ISO 2012b; OECD
2016b), life-long tests with terrestrial plants (OECD 2006b) or assays with long term
cultivation of soil microbial communities for effects on carbon and nitrogen transformations (ISO 2012d; OECD 2000a, 2000b). However, because of large time and
1 Because of their fast life cycle, high plasticity and adaptability, assays with bacteria and other
microorganisms are not usually among the basic regulatory batteries for ecotoxicity testing.
Nevertheless, many bacterial models exist and play inevitable roles. For example, in testing for
genotoxicity (Ames test with Salmonella typhimurium) or in rapid screenings (30-min assay with
bioluminescent bacteria Aliivibrio (formerly Vibrio) fisheri, also known as Microtox test).
27 Ecotoxicology of Environmental Pollutants
553
assessing and predicting the ecotoxicological effects.
Trophic Levels & Batteries of Assays The approach considers the key structural
pillars of biological communities, i.e., trophic levels. In principle, representatives of
biological species from the groups of producers (autotrophic organisms like algae
and plants), consumers (invertebrate and vertebrate animals), and decomposers
(microorganisms)
1 are selected as model organisms and used in batteries of bioassays for testing of ecotoxicity.
The bioassays recommended for ecotoxicity testing within regulatory frameworks (including chemical safety as well as risk management and remediation)
need to be validated to assure repeatability and quality of the results using standardized guidelines that are currently available through international organizations
such as OECD or ISO.
The broadly used bioassays recommended by regulations include usually
short-term exposure (acute) tests. These have both advantages (e.g., possibility
to maintain the model organisms in laboratory, good standardization, time and
cost-effectiveness) and disadvantages (lower sensitivity in comparison to wild
species, lower representativeness for environmentally relevant long-term chronic
exposures, etc.).
• Aquatic Environment The most commonly used assays are 72–96 h algal
growth inhibition test with, e.g., Scenedesmus subspicatus (OECD 2011),
24–48 h immobilization test with crustacean Daphnia magna (OECD 2004),
96 h acute test for lethality with adult fish (OECD 1992), currently promoted
alternative 96 h toxicity test with zebrafish Danio rerio embryos (OECD 2013),
and 16 h bacterial growth inhibition test with Pseudomonas putida (ISO 1995)
• Terrestrial and Soil Environment Commonly used bioassays include 7–14-day
acute test for lethality with earthworms Eisenia fetida (OECD 1984; ISO 2012a),
96 h root elongation test with plants, e.g., Lactuca sativa (OECD 2006a; ISO
2012c), 24 h acute test for lethality of nematode Caenorhabditis elegans (ASTM
2014), or 6 h test for effects on microbial nitrification in soil (ISO 2012e).
Standardized longer exposure assays testing for population-relevant endpoints
such as reproduction are also available. For example, 21-day reproduction test with
D. magna (OECD 2012) or reproduction test with enchytraeids (ISO 2014b; OECD
2016a), springtails (ISO 2014a; OECD 2009), and earthworms (ISO 2012b; OECD
2016b), life-long tests with terrestrial plants (OECD 2006b) or assays with long term
cultivation of soil microbial communities for effects on carbon and nitrogen transformations (ISO 2012d; OECD 2000a, 2000b). However, because of large time and
1 Because of their fast life cycle, high plasticity and adaptability, assays with bacteria and other
microorganisms are not usually among the basic regulatory batteries for ecotoxicity testing.
Nevertheless, many bacterial models exist and play inevitable roles. For example, in testing for
genotoxicity (Ames test with Salmonella typhimurium) or in rapid screenings (30-min assay with
bioluminescent bacteria Aliivibrio (formerly Vibrio) fisheri, also known as Microtox test).
27 Ecotoxicology of Environmental Pollutants
553